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c wmf/MMM Patented Nov. 2, 1948 FUSE JohnC. Gillette, Washington, D. C., and Braxton H; Tabb, Jr., Arlington, Va.

Application February 29, 1944, Serial No. 524,430

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 6 Claims.

y The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a delayed arming mechanism for projectile fuses.

In order that the inertia elements in fuses employing them, function properly, the projectile should be stable in flight. This desired stability in interfered with if the rifling of the gun is worn,

in which event there is consequent danger of premature functioning of the inertia elements before the projectile has gotten out of the gun or far enough away from it. An object of this invention is to provide a mechanism that will positively delay the arming of the fuse regardless of the Y condition of the gun, for a time that will allow the projectile to become stable, thereby eliminating the possibility of premature burst at any stage in the projectile's ilight, and one that will arm the fuse at greatly reduced rotational velocity and which when once armed remains so regardless of such reduced velocity.

The invention contemplates the provision of a delay mechanism in which there is a weighted element responsive to centrifugal force, but held locked until released by the rotation of the projectile .to cause movement of other elements in a gear train, the speed of which depends upon escapement devices that allow the gears to progress one tooth at a time until a point is reached, according to the setting of the fuse, at which a ring pin carrying rotor is unlocked and surrendered to the effective influence of centrifugal force which then acts. to rock the rotor to armed position or that in which the firing pin is brought into alignment with the primer or detonator to re the -charge upon the forward movement of a detonaftor carrying plunger upon the impact of the proictile. The present construction and arrangement is such that when the fuse is armed the. rotor will function with certainty to keep it armedat a vastly lower rotational velocity than with devices for this purpose heretofore employed.

In the drawings illustrated the invention: Figure 1 is a central section of the fuse, a portiori'ofia shell, the head of the fuse being shown in elevation in broken association with the fuse, and showing the firing pin carrier for the rotor in locked unarmed position.

v Figure 2 is a section of the fuse at right angles to Figure 1, showing the fuse armed.`

Figure 3 is a section on the line 3-3 of Figure l, Figure 4 is a section on the line 4--4 of Figure 1. Figure 5 is a section on the line 5--5 of Figure 1.

2 Figure 6 is a detail view of the.. gear train of the escapement mechanism as it appears looking to the left in Figure 3. v

Referring to the drawings and particularly to Figure 1, the numeral I designates the fuse body reduced at its rear end as indicated at 2, andV threaded into the shell 3 as usual.

Secured to the fuse body in appropriate manner is the ogive 4 that merges into thefuse head 5. In the present instance, the head may contain'a firing pin and detonator assembly which is no part of the invention, and therefore, need not be shown or further described. However, there is connected with this assembly a ilash tube 6, a part of which is shown in both Figures 1 and 2 threaded at its rear end into the bore 1 in a boss I positioned centrally on the fuse body I. The body is provided with abore 8 forming a continuation of the bore in the flash tube 6.

rihe numeral 9 designates the plunger body hereinafter referred to as the plunger. This is slidable in a recess Illin the fuse body and has cylindrical passage I I in axial alignment with the bore 8.

A spiral spring I 2 seated on a shoulder I3 on the plunger and bearing against a similar shoulder I4 on the fuse body serves to hold the plunger normally in engagement with the shoulder I5 of a retaining ring I6 threaded into the fuse body.

Referring particularly to Figures l, 2, and 4, the numeral I'I indicates the firing pin carrying rotor which is positioned in the space between thefront end of the plunger 9 and the fuse body. The rotor is pivotally attached to the fuse body by a pivot pin I 8 which extends considerably below the rotor and into a socket I9 in the plunger, in which socket it has a working t. The socket is of a depth to permit the plunger to move forward in the recess I0 sufciently for the firing pin 20, which is carried by the rotor, to contact the primer or detonator assembly, when the rotor'is rocked to bring the firing pin, into vertical alignment with the detonator.

The rotor I1 has a recess 2I at its end opposite its :pivotfor the reception of a rotor locking pin slidably mounted in an oblique aperture 23 in the front end ofthe fuse body. The inner end of this `pin extends normally into the recess 2| locking the rotor against movement and the fuse in un" armed position. s

The aperture 23 extends through the front of v vthe fuse body, and the outer end of the locking pin thereinv normally engages the rear side of a gear wheel 24 (Fig. 5) provided with a radial recess 25' to receive said pin when, at the proper time, the pin has been moved from normal position by centrifugal force generated in the flight of the projectile. This wheel 24 is rotatably mounted on the front of the fuse body and forms an important element of the delay mechanism which will now be more fully described.

In front of the wheel 24 there are two spaced plates 25 and 26 held in spaced relation by identical posts 21. A pinion 28 on the shaft 28 journaled in the fuse body and extending through the plates, meshes with the recessed gear 24 (Figure and fixed to the pinion shaft 28 between the plates there is a gear wheel 29 meshed with a similar gear wheel 3|] (Figure 6), on the shaft 30' journaled in the plates and extending beyond the plate 25, and having fast thereto a wheel 3| provided with a, segment of teeth 3|. Meshing with some of these teeth is a rack segment 32 which normally holds the wheel locked or in the position shown in Figure 3. The rack segment is carried by a dat bowed spring 32 whose ends embrace short studs 33 in the plate 25, the spring being so shaped and so mounted on the studs as to permit movement of the segment under the influence of centrifugal force, to unlock the wheel 3l, to permit its rotation. A weight 34 is attached to the wheel 3| and a stop in the way of a stud 35 on the plate 25 limits the clockwise movement of the wheel. The rotation of the wheel in the opposite direction is limited by the rack segment 32. Centrifugal force, acting upon the wheel 3| through the weight 34 rotates the wheel as fast as the escapement elements, which will now be described, will permit. Mounted on the pinion shaft 28 above the top plate 25 is an escapement ratchet wheel 36 which cooperates with an escapement pawl 31 pivoted at 38 to the plate 25. This pawl has a weighted arm 3T' extending some distance from its pivot, the weight, shape and position of the arm being such as to assure oscillation of the pawl in proper time to permit the ratchet and consequently the gear train controlled by it, to move the distance of one tooth at a time, as is usual in escapement mechanism.

The amount of movement to be allowed for the wheel 3| and consequently the amount of movement of the wheels controlled thereby, will be determined by the number of teeth on the wheel and the initial position of the rack segment relative to said teeth. However, we do not desire to be understood as limiting ourselves to the particular gear train or the number of wheels employed to bring about the movement required to unlock the rotor and permit it, by centrifugal force, to be swung to position to bring the firing pin in line with the detonator assembly to ignite the detonator when the plunger 9 moves forward upon impact of the projectile.

Eccentrically mounted in the fuse body 9 is a detonator assembly 39 (Figures 2 and 4) communicating with the main charge chamber of the projectile by a ash passage 40 in line with which assembly the ring pin will be brought during the flight of the projectile, and when the fuse is armed. This alignment between the firing pin and the detonator assembly can only occur after the rotor locking pin 22 is withdrawn by centrifugal force from the recess 2| in the rotor, which can only occur when the recess 25' in the wheel 24 (Figure 5) arrives in position to receive the outer end of the locking pin.

In the fuse body, above the rotor and intersecting the bore 8, is an interrupter 40 having an aperture 4| therethrough adapted to be brought into registry with said bore or not, accordingly as to whether the head portion detonation assembly is to be used in connection with a quick or a delayed action fuse.

In operation, assuming the ash passage 6 and bore 8 to be closed as shown in Figure 1, the rotor is locked by locking pin 22, as shown best in Figure 4, with its firing pin 20 in line with the axis of the projectile, but eccentric to the detonator assembly 39. When the projectile is red, and after setback diminishes sufficiently for rotational forces to become operative, the wheel 3|, after it has been released from the rack segment 3, will tend to rotate and act much as the main spring of a clock mechanism. The wheel 3| will rotate the wheel 30 and through the pinion 28 will rotate the recessed wheel 24 in the direction of the arrow until the recess 25 in said wheel is brought opposite the rotor locking pin 22. The pin will now be moved by centrifugal force from the recess in the rotor and permit the rotor to be rotated or rocked until it is stopped by contact with the wall of the recess l0 in the fuse body, at which point of stoppage it brings the firing pin in line with the detonator assembly 39, and the fuse will be armed. Previously to this armed condition, the locking pin has been prevented from moving due to its contact with the rearside of the wheel 24, and has been waiting for the arrival of the recess 25' to release it.

We claim:

l. In a fuse for attachment to a shell containing an explosive charge, a delay arming mechanism comprising a body having a recess therein, a plunger in said recess mounted for forward movement upon impact, a rotor pivotally mounted on said body and carrying a firing pin, said rotor being operable by centrifugal force and normally locking said plunger against movement, a detonator assembly in the plunger, and eccentric to the axis of said plunger, centrifugal force responsive means for normally locking the rotor against movement, an escapement mechanism comprising a centrifugal force responsive element for releasing said rotor locking means to permit said rotor, under the influence of the centrifugal force to bring its firing pin in line with the detonator assembly to ignite the detonator therein upon forward movement of the plunger upon impact.

2. In a fuse for attachment to a shell containing an explosive charge, a delay arming mechanism comprising a body having a recess therein, a plunger spaced from the forward end of said recess and mounted for forward movement in the recess upon impact, a rotor pivotally mounted in the body and normally blocking the forward movement of the plunger, said rotor being operable by centrifugal force to release the plunger, a detonator assembly eccentrically mounted in the plunger, a ring pin carried by the rotor, a rotor locking pin slidably mounted in said body and normally engaging the rotor and locking it against movement, said locking pin being operable by centrifugal force to release said rotor, and means comprising a centrifugally operated device including a directly connected movable member and means to control the rate of its movement, engaging said locking pin to hold the same in locking position initially and operable b.v centrifugal force to clear the pin to permit disengagement of the pin and said rotor at a predetermined time to allow the rotor to be rotated by centrifugal force to position to arm the fuse.

3. In a fuze for attachment to a shell containing an explosive charge, a delay arming mechanism comprising a body having a recess therein, a plunger 'in said recess mounted for forward movement upon impact, a rotor pivotally mounted on the body normally in the path of and preventing movement of said plunger and being responsive to centrifugal force to move clear of said path to an armed position, a forwardly exposed detonator mounted in the plunger, a firing pin carried by the rotor normally out of line with said detonator but in line therewith when the rotor is in said armed position, movable rotor locking means normally locking the rotor in unarmed position but movable in response to centrifugal force to an unlocking position free of the rotor, a movable delay member carried by said body normally in stopping engagement with said rotor locking means and movable by centrifugal force to a clearing position free of the rotor locking means, said delay member having stopping relation to the rotor locking means through an initial part of the movement of the delay member, and an escapement mechanism operatively connected with said delay member to limit its rate of movement.

4. The invention of claim 3 characterized in that the said delay member comprises a gear wheel against one side of which the rotor locking means normally bears said Wheel being provided with a radial recess arranged to receive the rotor locking means at a predetermined terminal position of the gear.

5. In a fuze for attachment to a shell containing an explosive charge, a delay arming mechanism comprising a body having a recess therein, a spring-restrained plunger therein having a detonator assembly mounted eccentrically of the plunger, a rotor pivotally mounted on said body and operable by centrifugal force, said rotor having a firing device normally out of line with said detonator assembly, means for locking the rotor in unarmed position, comprising a recess in the rotor, a rotor locking pin slidable in the fuze body and operable by centrifugal force, a Wheel on the fuze body and having a recess therein, said Wheel normally holding the pin in rotor locking position, and an escapement mechanism for controlling the movement of said wheel to bring the recess therein to position to receive said pin to unlock 6 the rotor and permit it to move to position to arm the fuze.

6. In a fuse for attachment to a shell containing an explosive charge, a delayed arming mechanism comprising a body having a recess therein, a plunger in said recess mounted for forward movement therein upon impact. a rotor pivotally mounted in said body forward of said plunger and carrying a firing pin, said rotor being operable by centrifugal force and normally locking the -plunger against forward movement, a detonator assembly eccentrically mounted in the plunger and having a passage `communicating with the explosive charge, a rotor locking device operable by centrifugal force to unlock the rotor and permit it to bring its firing pin in line with the detonator assembly to ignite the same upon the forward movement of the plunger, and escapement mechanism comprising a motor Wheel responsive to centrifugal forces, means also responsive to said forces for normally locking the motor Wheel against rotation, a gear train operable by said motor Wheel when said Wheel is released, and including a gear wheel against one side of which the rotor locking device normally rests to lock said device against movement, said gear Wheel being provided with a recess to receive said device at a predetermined time to permit movement of said device to release the rotor and permit it to be moved to armed position.

JOHN C. GILLETTE. BRAXTON H. TABB, J R.

REFERENCES CITED The following references are of record in the' le of this patent:

UNITED STATES PATENTS Number Name Date 1,568,527 Pearson Jan. 5, 1926 1,726,325 Varaud Aug. 27, 1929 1,772,613 Mellstrom Aug. 12, 1930 2,043,266 Rogers June 9, 1936 FOREIGN PATENTS Number Country Date 151,632 Great Britain Dec. 28, 1921 162,099 Great Britain Apr. 28, 1921 

